Referenced in: none

Automatically associated channels: Kv10.1

Title: Convergent Evolution of Sodium Ion Selectivity in Metazoan Neuronal Signaling.

Authors: Maya Gur Barzilai, Adam M Reitzel, Johanna E M Kraus, Dalia Gordon, Ulrich Technau, Michael Gurevitz, Yehu Moran

Journal, date & volume: Cell Rep, 2012 Jul 26 , ,

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/22854023

Abstract
Ion selectivity of metazoan voltage-gated Na(+) channels is critical for neuronal signaling and has long been attributed to a ring of four conserved amino acids that constitute the ion selectivity filter (SF) at the channel pore. Yet, in addition to channels with a preference for Ca(2+) ions, the expression and characterization of Na(+) channel homologs from the sea anemone Nematostella vectensis, a member of the early-branching metazoan phylum Cnidaria, revealed a sodium-selective channel bearing a noncanonical SF. Mutagenesis and physiological assays suggest that pore elements additional to the SF determine the preference for Na(+) in this channel. Phylogenetic analysis assigns the Nematostella Na(+)-selective channel to a channel group unique to Cnidaria, which diverged >540 million years ago from Ca(2+)-conducting Na(+) channel homologs. The identification of Cnidarian Na(+)-selective ion channels distinct from the channels of bilaterian animals indicates that selectivity for Na(+) in neuronal signaling emerged independently in these two animal lineages.